It is common practice to make water tanks, or towers, from sheet steel plates. However, to construct a very tall tower where there are significant hydraulic pressures in the lower part of the tower, it has been the usual case to make the tower double-skinned at the bottom. Hitherto it has been practicable to make a double-skinned tower only if the tower is of welded construction. Welding is very expensive however since skilled operators are required, and the need to stress-relieve the welds poses further limitations.
One of the problems with bolting plates together is that the ends of the bolts protrude. The tower constructor cannot simply bolt a set of plates to encircle an existing set: the plates must be interleaved together if he wishes to provide an effective double-skinning arrangement by bolting.
An advantage of bolting is that the plates can be pre-finished. Glass-coating the steel is a very effective protection for water storage tanks: the glass coating is applied to both sides of the plates and provides a very hard inert barrier (about 0.008 inches thick) of silica glass, which is chemically and mechanically bonded to the steel.
Another problem though with bolting is that not all the edges of the plates can be overlapped and bolted tightly together. Not, at least, if the overlapping is to occupy only a margin at the edge of the plates, and also not if a gap or space between the plates is to be avoided. A further problem is that where the edges of the plates are in abutment, a potential leakpath arises, which must be accounted for.